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Home & garden.

14 July 2021

How to grow spring onions and best varieties

Find out how to grow spring onions for salads and stir fries. Discover our best spring onion varieties and tips for how to grow them.
CT
Ceri Thomas
Spring onions

Spring onions are ideal for filling gaps in the veg patch. You can also grow them in containers and raised beds. They can be ready to harvest just eight weeks after sowing, and if you sow little and often you can be picking fresh crunchy onions for salads and stir-fries for many months. You can even grow some varieties to full-sized onions.

How to grow spring onions: month by month

JanuaryFebruaryMarchAprilMayJune

SOWSOW/PLANTSOW/PLANTSOW/PLANTSOW/PLANT
JulyAugustSeptemberOctoberNovemberDecember
SOW/PLANTSOW/PLANTSOW/PLANT


Best spring onion varieties

Which? members can log in now to see the full results and which are our Best Buy varieties. If you’re not a member, join Which? to get instant access.

Best Buy spring onions
What it looks likeVariety nameYield from a 1.5m row
1.7kg
Described as a bulbing bunching onion, this variety was a little shorter overall than other varieties, but with a good-sized blanched section. Harvested when small, the bulb was less pronounced, but when allowed to grow on the bulb provided more onion per plant and didn’t adversely affect the ease of peeling. All but a handful of onions were well developed and a good size. It is a winter-hardy variety that can be sown in August or September for overwintering; it also holds an RHS Award of Garden Merit.
What it looks likeVariety nameYield from a 1.5m row
1.59kg
This variety was the best-performing red spring onion in our trial, producing 1.59kg of onions and just a few that were undersized. The bulb-shaped ends made it a little tricky to strip off the outer leaves, which marked it down a bit, but the quality was good. It’s a great choice for adding a little colour to your salads, and it can be used as a dual-purpose onion: pick young for salad onions or allow to bulk up to small onion size.
What it looks likeVariety nameYield from a 1.5m row

How we test spring onions

We selected 19 widely available varieties of spring onions, including previous Best Buys and those with an RHS Award of Garden Merit. We included both red and white onions.

In early June, we sowed our spring-onion seeds direct into drills at our trial site in Cambridgeshire and used sprinkler irrigation to water the plot.

We weeded between the rows of spring onions every two weeks or so and watered the plot with a sprinkler after weeding.

In mid-August, we harvested and recorded the number and weight of usable onions for each variety. We also made a note of any that were too small or underdeveloped, and rated each variety for overall quality and ease of stripping the outer foliage to leave a clean shank and bulb.

When to sow

Despite their name, spring onions can be sown from February to July. Sow small amounts at intervals in fertile, well-drained soil and protect early sowings with cloches or fleece. From August onwards you can sow winter-hardy varieties, such as ‘White Lisbon’ and ‘Ramrod’.

You can sow spring onions in various ways. To sow where they are to grow, sow thinly 1-1.5cmdeep into drills leaving enough space to hoe between rows. You can also sow in containers and raised beds. Alternatively, sow in modular trays indoors and plant out once the seedlings are large enough to handle.

Caring for your plants

Keep the ground moist and weed free; fast-growing weeds can out-compete spring-onion seedlings. Onions germinate slowly, so weed carefully between rows until plants are established. Hoe regularly to keep the weeds down and avoid competition. 

Watch out for signs of bolting (the production of flower heads) in hot weather. Snip off any flower heads that form and use the onions as soon as possible.

How and when to harvest

Pull spring onions when they’re pencil-thick and strip off outer leaves to leave a clean stem. Early sowings will be ready in around 10-12 weeks; early summer sowings can be ready to harvest in as little as eight weeks.

Common growing problems

Rust

Leek rust is a fungal disease that affects members of the allium family – leeks, garlic, onions and spring onions. It appears as bright orange spots on the leaves. There is no chemical control available to gardeners. Rust is more prevalent in humid conditions; allowing space between plants improves airflow and reduces humidity.

Read more about leek rust